Old houses that are built between mid 19th to 20th Century, might have possibly toxic materials. Lead pipes were a common thing back then and a service line that uses lead usually causes water contamination. Moreover, even though older homes are made up of more solid materials, they eventually erode with time and ultimately start causing problems. Old houses have pipes buried underneath the ground or covered in concrete slabs. If these pipes shift downwards, creating a pipe belly. These bellies restrict the flow of water and cause clogs.